1. Technical Field
The present invention relates generally to the area of identification devices. More particularly, the present invention provides a radio-frequency identification system with features to reduce a party's ability to tamper with the identification devices or to track the identification devices on a global scale. The invention is particularly useful as a theft/fraud preventive in the context of a retail store or as a means of inventory control when accuracy is critical, such as with an inventory of pharmaceuticals in a clinical setting.
2. Description of Related Art
Radio-frequency identification (RFID) technology provides an inexpensive and simple way to mark physical objects with machine-readable information. In this application, the term “machine-readable” refers to those media that are readable only by a machine; such media are almost always machine written as well. RFID has many advantages over other machine-readable information media. Unlike magnetic media, RFID tags do not require a reader to make contact with the tag to read the information out. Unlike bar codes, RFID tags can be easily rewritten and do not require that the tag be visible when read.
RFID tags are electronic devices. They are generally composed of an antenna and an integrated circuit. The antenna is used for sending and receiving data as radio-frequency signals. The integrated circuit contains non-volatile memory, modulation circuitry (for facilitating radio communication), and control logic. Thus, RFID tags are memory devices that are read and written to using radio-frequency signals.
RFID tags are passive devices. That means that they need not include a power supply. RFID tags receive all the power they need to operate from the radio-frequency signal emitted by RFID tag readers or writers. This makes it possible to manufacture RFID tags of very small size. Advancements in RFID tag fabrication technology have also made it possible for RFID tags to be manufactured at very small sizes. For instance, early RFID tags used large inductive antennas; more modern tags use capacitive antennas, which can be printed on packaging using conductive ink in a way that blends in with other printed marking. With this new antenna manufacturing technique the integrated circuit can simply be glued on to the antenna looking, perhaps, like just a “dot” in the product logo or other printing.
RFID tags, because of their small size, are easily incorporated into other products. For instance, RFID tags can be easily sewn into clothes or attached to product packaging, or incorporated into product markings. This makes them prime candidates for storing product information, such as universal product codes (UPCs) or price information, in a retail product, much as bar codes do for supermarket products today.
Another use for RFID tags, one that has already gained wide acceptance, is to use RFID tags as a theft detection system. In such a system, RFID-tagged merchandise, when transported past a reader device in front of the exit to a store, triggers an alarm, unless the tag has been reprogrammed at the point-of-sale when the item is purchased.
Three problems with the widespread use of RFID tags on merchandise occur, however. The first is that many current RFID tags can be readily tampered with. Current RFID tags generally impose no access control requirements and may be read from and written to freely. Thus, a store employee with less than honorable intentions might reprogram the tag on a particular piece of merchandise such that when the employee buys the merchandise from the store, the employee is undercharged.
The second problem is one that also occurs with some frequency with bar codes. Sometimes the point-of-sale terminal at which an item is being purchased is programmed with incorrect price information. This situation can result in the customer being overcharged or even undercharged. Because the RFID tag is machine-readable only, it provides no price information to the cashier. Thus, there is often no way for the cashier to detect a mistake in a customer's receipt.
The third problem is that the widespread use of RFID tags on merchandise such as clothing would make it possible for the locations of people, animals, and objects to be tracked on a global scale—a privacy invasion of Orwellian proportions.